Whether an inspiration is evil or good, unjust or just -depends on what is being done and whether it is halaal or haraam.
Allah reserves for Himself the right to inspire just guidance and has stated this clearly and unambiguously to the whole world.
The falsehood and unjust tricks of shaytaan will be undone Allah will establish true justice as soon as shaytaan has played his weak hand.
Let us not be foolish enough to compare the illusory power of shaytaan and his followers with that of the creator and sustainer of the heavens and the earth who has no equivalent or real competition. He is testing people as He tested during the time of Musa :saws: pharaoh was foolish enough to try competing against Allah on equal chances as he had requested and Allah had allowed, however pharaoh's continued falsehood and injustice hemmeded in pharaoh and his followers.
We've all received the just guidance of Allah and have no excuse to deny Him, it is best that we submit to truth and justice and refrain from pretending that the enemies of truth and justice are somehow equal to Allah.
وَمَا مَنَعَنَا أَن نُّرْسِلَ بِالآيَاتِ إِلاَّ أَن كَذَّبَ بِهَا الأَوَّلُونَ وَآتَيْنَا ثَمُودَ النَّاقَةَ مُبْصِرَةً فَظَلَمُواْ بِهَا وَمَا نُرْسِلُ بِالآيَاتِ إِلاَّ تَخْوِيفًا {59
And nothing hindered Us from sending of the signs, except that the previous lot rejected them. And We gave to Thamud the she-camel, to make them see, but they oppressed her, and We do send signs except to put fear.
مَثَلُ الَّذِينَ حُمِّلُوا التَّوْرَاةَ ثُمَّ لَمْ يَحْمِلُوهَا كَمَثَلِ الْحِمَارِ يَحْمِلُ أَسْفَارًا بِئْسَ مَثَلُ الْقَوْمِ الَّذِينَ كَذَّبُوا بِآيَاتِ اللَّهِ وَاللَّهُ لَا يَهْدِي الْقَوْمَ الظَّالِمِينَ {5
The likeness of those who were burdened with the Taurah, but who subsequently failed to carry them, is as the likeness of a donkey who carries scrolls. Evil is the example (or the likeness) of people who deny the Ayat (proofs, evidences, verses, signs, revelations, etc.) of Allah. And Allah guides not the people who are unjust.
وَمَا أَرْسَلْنَا مِن قَبْلِكَ مِن رَّسُولٍ وَلَا نَبِيٍّ إِلَّا إِذَا تَمَنَّى أَلْقَى الشَّيْطَانُ فِي أُمْنِيَّتِهِ فَيَنسَخُ اللَّهُ مَا يُلْقِي الشَّيْطَانُ ثُمَّ يُحْكِمُ اللَّهُ آيَاتِهِ وَاللَّهُ عَلِيمٌ حَكِيمٌ {52
022:052 Khan
:
Never did We send a Messenger or a Prophet before you, except that when he did recite the revelation or narrated or spoke, Shaitan (Satan) threw (some falsehood) in it. But Allah abolishes that which Shaitan (Satan) throws in. Then Allah establishes His Revelations. And Allah is All- Knower, All-Wise:
86. Say: "No reward do I ask of you for this (Qur'an), nor am I a pretender.
87. "This is no less than a Message to (all) the Worlds.
88. "And ye shall certainly know the truth of it (all) after a while."